It is well established that social context impacts physical and mental health. People with more social connections experience less illness and recover more quickly and thoroughly when they do. Understanding the mechanism by which social context influences wellbeing will allow for the development of new interventions and treatments for pathology, and in particular psychopathy. Despite accumulating evidence that illustrates a relationship between social relationships and wellbeing, little is known about the biological mechanisms that subserve that relationship. One possible mechanism is that social context influences brain anatomy which in turn influences wellbeing. New evidence collected in people and monkeys illustrates that the more social relationships an individual has, the larger the volume of the amygdala and other brain regions critically important for the generation and regulation of emotions. These data point to a relationship between social network size and the structure and function of brain areas that are important for emotion and wellbeing, although they leave a number of important questions unanswered. First, is it only social network size that matters, or does an individuals social role impact neuroanatomy? Second, how does an individuals social role early in development influence neuroanatomy across the life span? Third, how does emotional brain neuroanatomy mediate the impact of social life on emotional processing? The goal of the proposed work is to answer these questions. To that end, I will first characterize individuals social roles using formal social network analyses. Such analyses provide information about the number of social connections an individual has, but also about what specific role the individual plays in that network. Individuals will then undergo neuroimaging in order to characterize the structure and functional connectivity neuroanatomical regions of interest. They will also complete testing to characterize their emotional processing. I will first examine whether social role influences brain neuroanatomy and emotional processing using a cross sectional study with adult subjects (Specific Aims 1, 3). Next I will examine whether social roles early in development influence neuroanatomy and the capacity for developing new social relationships across a critical developmental period (childhood through young adulthood) using an experimental longitudinal study design (Specific Aim 2, 3). Together, these data will allow for the evaluation of the impact of social roles on emotional processing as mediated by neuroanatomy across the life-span.